Angular2：如何从子组件调用主组件函数

Question

How to call main component function from a child component when I have deep nested hierarchy?

I have 3 components, button component I'm including inside browser component and browser component I'm including inside main component.

On click of button I need to call a function which is inside main component.

Button Component

@Component({
    selector: 'cb-button',
    templateUrl: 'cb-button.component.html',
    styleUrls: ['cb-button.component.scss']
})

export class CbButtonComponent {

     @Output() onClick: EventEmitter<any> = new EventEmitter();

     onBtnClick(): void {
        this.onClick.emit();
    }
}

button component html

<div (click)="onBtnClick()">
    <button>btn</button>
</div>

browser component

@Component({
    selector: 'topology-browser',
    templateUrl: 'topology-browser.component.html',
    styleUrls: ['topology-browser.component.scss']
})

export class TopologyBrowserComponent {

   @Input('campus') campus: Campus;
}

browser component html

<div>
<h1>browser title</h1>
<cb-button (click)="editCampus()"></cb-button>
</div>

and finally in main component i'm including browser component

main-component.ts

editCampus() {
  alert('clicked');
}

html

<topology-browser [campus]="campus"></topology-browser>

when I click button I'm getting below error

Errorself.parentView.context.editCampus is not a function

Answer 1

• If you know what type the root component is, you can use Pengyy's method.

• If you don't know what type in advance but you can customize the root component to your needs, a shared service is a good way.

• A more generic way is to get the root component by injecting ApplicationRef (not actually tested myself):

constructor(app:ApplicationRef, injector: Injector) {
  app.components[0].someMethodOnMainComponent();
}

https://angular.io/docs/ts/latest/api/core/index/ApplicationRef-class.html

Answer 2

As I know there are two ways for your situation:

• inject the parent component to child component
• use EventEmitter

Since you have more than two layers, injecting MainComponent to ButtonComponent is much more simply to implement:

import {Component, Inject, forwardRef} from '@angular/core';

// change the MainComponent to your real component name
constructor(@Inject(forwardRef(() => MainComponent)) private main:MainComponent)

Answer 3

export class CbButtonComponent {

     @Output() onClick: EventEmitter<string> = new EventEmitter<string>();

     onBtnClick(): void {
        this.onClick.emit('clicked');
    }
}

In your browser component

HTML

<div>
    <h1>browser title</h1>
    <cb-button (onclick)="buttonclicked($event)"></cb-button>
</div>

Component

@Output() buttonClick: EventEmitter<string> = new EventEmitter<string>();

buttonclicked(clickedEvent){
   this.buttonClick.emit('clicked');
}

In your parent Main component

<topology-browser [campus]="campus" (buttonClick)="buttonComponentClicked($event)"></topology-browser>

Component code

buttonComponentClicked(buttonClicked){
       /// method calls goes her

}

By this way you are notifying the browser component with the click which is captured again in the main component and handled

Answer 4

You may try the below. I have not tried this but am guessing it might work. The button component emits an event which is being caught by the main component.

You may also pass data via a common service and injecting that service into the child component and calling a service function which updates a service observable which is subscribed by the main component

Your main component

@Component({
  template `
    <button-comp (onClick)="mainMethod($event)"></button-comp>
  `,
  directives: [ ButtonComponent ]
})
export class MainComponent {
  (...)

  mainMethod(event) {
    console.log(event)
  }
}

your button component

@Component({
    selector: 'cb-button',
    templateUrl: 'cb-button.component.html',
    styleUrls: ['cb-button.component.scss']
})

export class CbButtonComponent {

     @Output() onClick: EventEmitter<any> = new EventEmitter();

     onBtnClick(): void {
        this.onClick.emit('hello');
    }
}

button component html

<div (click)="onBtnClick()">
    <button>btn</button>
</div>